Programming A Memory Device

ABSTRACT

A memory device includes a memory cell array and a memory controller. The memory cell array includes a plurality of memory blocks. Each of the memory blocks includes a plurality of word lines. A plurality of memory chunks is coupled to at least one of the word lines. The memory controller is configured to program data to a particular memory chunk of the plurality of memory chunks by performing a chunk operation that includes selecting a particular word line from the plurality of word lines, selecting a particular memory chunk from the plurality of memory chunks that are coupled to the particular word line, and applying a program voltage to a particular memory block corresponding to the particular memory chunk to program data to the particular memory chunk.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims priority toU.S. application Ser. No. 16/281,258, filed on Feb. 21, 2019.

TECHNICAL FIELD

The present application relates to a memory device. In particular, thepresent application relates to programming data to memory cells in amemory device.

BACKGROUND

Memory cells can be programmed by applying a set of voltages during aprogramming cycle. In particular, to program data to a high-densitymemory device, e.g., a high-density NAND flash memory device or a NORflash memory device, different levels of voltages can be applied to thehigh-density memory device at different timings for suitable periods.

SUMMARY

The present application describes techniques to program data to memorycells in a memory device. In particular, where a memory controllerprograms multi-level data to multiple memory chunks in a memory block, adisturbance can occur between memory chunks. Moreover, where a memoryblock has a status of wear-out or broken, the memory block is morelikely to have the disturbance problem. If there is a disturbancebetween memory chunks, the memory controller may program data to aparticular memory chunk incorrectly. Thus, the disturbance can causereliability problems in a memory device. In addition, where a memorydevice requires high reliability, e.g., a memory device is used forcommunication devices, the disturbance problem should be avoided toguarantee a certain level of reliability.

The techniques disclosed in the present application can reduce orsubstantially eliminate the disturbance problems occurring in a memorydevice. In particular, a memory controller obtains data about an errorrate of a memory block and determines which programming operations thememory controller performs. For example, where the memory block has ahigh error rate, the memory controller can perform one-shot programmingoperations to avoid the disturbance. On the other hand, where the memoryblock has a low error rate, the memory controller can performmulti-level programming operations to increase the efficiency of theprogramming operations. As a result, the techniques can improve thereliability of the memory device without compromising the efficiency ofthe memory device.

In general, one innovative aspect of the subject matter described inthis specification can be implemented in a memory device comprising amemory cell array and a memory controller. The memory cell arrayincludes a plurality of memory blocks. Each of the memory blocksincludes a plurality of word lines. A plurality of memory chunks iscoupled to at least one of the word lines. The memory controller isconfigured to program data to a particular memory chunk of the pluralityof memory chunks by performing a chunk operation that includes selectinga particular word line from the plurality of word lines, selecting aparticular memory chunk from the plurality of memory chunks that arecoupled to the particular word line, and applying a program voltage to aparticular memory block corresponding to the particular memory chunk toprogram data to the particular memory chunk.

The foregoing and other implementations can each optionally include oneor more of the following features, alone or in combination. Inparticular, one implementation includes all the following features incombination. The memory controller may be configured to select theparticular word line from the plurality of word lines sequentially. Thememory controller may be configured to select the particular memorychunk from the plurality of memory chunks sequentially. The memorycontroller may be configured to select the particular word line from theplurality of word lines randomly. The memory controller may beconfigured to select the particular memory chunk from the plurality ofmemory chunks randomly. The memory controller may be configured toperform the chunk operation to the particular memory block by providinga program voltage that is between 12 V and 26 V.

The memory device may include an error detection circuit that isconfigured to detect one or more errors that occur in the particularmemory block and generate an error rate. The memory controller may beconfigured to perform the chunk operation upon the error rate satisfyinga threshold value.

The memory device may include a plurality of bit lines, each of the bitlines being respectively coupled to one or more memory chunks of theplurality of memory chunks. The memory controller may be configured toperform the chunk operation to a single memory chunk in a bit line ofthe bit lines during a single cycle of the chunk operation.

Another innovative aspect of the subject matter described in thisspecification can be implemented in a memory device comprising a memorycell array, an error detection circuit and a memory controller. Thememory cell array includes a plurality of memory blocks. Each of thememory blocks includes a plurality of word lines. A plurality of memorychunks are coupled to at least one of the word lines. The errordetection circuit configured to detect one or more errors that occur inthe memory block and generate an error rate. The memory controller isconfigured to program data to a particular memory chunk of the pluralityof memory chunks by performing operations that include obtaining, fromthe error detection circuit, the error rate. When the error ratesatisfies a threshold, the memory controller determines a status of aparticular memory block. Based on the status of the particular memoryblock, the memory controller determines which programming operations toperform between a first programming operation and a second programmingoperation, and performs the determined programming operations to theparticular memory block.

The foregoing and other implementations can each optionally include oneor more of the following features, alone or in combination. Inparticular, one implementation includes all the following features incombination. The first programming operation may include selecting aparticular word line from the plurality of word lines, selecting aparticular memory chunk from the plurality of memory chunks that arecoupled to the particular word line, and applying a program voltage tothe particular memory block to program data to the particular memorychunk. The second programming operation may include selecting one ormore first memory chunks in the particular memory block, applying afirst program voltage to the particular memory block to program data tothe one or more first memory chunks simultaneously, selecting one ormore second memory chunks in the particular memory block, and applying asecond program voltage to the particular memory block to program data tothe one or more second memory chunks simultaneously.

Another innovative aspect of the subject matter described in thisspecification can be implemented in a method to program one or morememory cells of a memory device by a memory controller during aprogramming cycle. The method includes selecting, by the memorycontroller, a particular word line from a plurality of word linesincluded in a particular memory block of a plurality of memory blocks ina memory cell array of the memory device, where a plurality of memorychunks is coupled to at least one of the word lines. The memorycontroller selects a particular memory chunk from the plurality ofmemory chunks that are coupled to the particular word line. The memorycontroller applies a program voltage to the particular memory blockcorresponding to the particular memory chunk to program data to theparticular memory chunk.

The foregoing and other implementations can each optionally include oneor more of the following features, alone or in combination. Inparticular, one implementation includes all the following features incombination. Selecting the particular word line may include selectingthe particular word line from the plurality of word lines sequentially.Selecting the particular memory chunk may include selecting theparticular memory chunk from the plurality of memory chunkssequentially. Selecting the particular word line may include selectingthe particular word line from the plurality of word lines randomly.Selecting the particular memory chunk may include selecting theparticular memory chunk from the plurality of memory chunks randomly.Applying the program voltage may include providing a program voltagebetween 12 V and 26 V.

The method may include detecting, using an error detection circuit inthe memory device, one or more errors that occur in the particularmemory block. In response to detecting the one or more errors, the errordetection circuit may generate an error rate. Upon the error ratesatisfying a threshold value, the memory controller may apply theprogram voltage to the particular memory block corresponding to theparticular memory chunk to program data to the particular memory chunk.

Selecting a particular memory chunk from the plurality of memory chunksmay include selecting a single memory chunk in a bit line of a pluralityof bit lines in the memory device during a programming cycle. Each ofthe plurality of bit lines may be coupled to one or more memory chunksof the plurality of memory chunks.

The details of one or more examples of the subject matter described inthis specification are set forth in the accompanying drawings and thedescription below. Other potential features, aspects, and advantages ofthe subject matter will become apparent from the description, thedrawings, and the claim.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example memory device.

FIG. 2 illustrates an example hierarchy of a memory cell array in amemory device.

FIGS. 3A to 3C illustrate example memory chunks of a memory device.

FIGS. 4A and 4B illustrate example timing diagrams to performprogramming operations to memory chunks of a word line.

FIGS. 5A and 5B illustrate example timing diagrams to performprogramming operations to word lines of a memory block.

FIG. 6 illustrates an example diagram of one-shot programming operationsfor a particular memory chunk in a memory block.

FIGS. 7A and 7B illustrate example diagrams to perform programmingoperations to a particular memory block.

Like reference numbers and designations in the various drawings indicatelike elements. It is also to be understood that the various exemplaryimplementations shown in the figures are merely illustrativerepresentations and are not necessarily drawn to scale.

DETAILED DESCRIPTION

A memory cell in a memory device can be programmed, e.g., data can bewritten to, read from, or erased from the memory cell, by applying asuitable voltage to the memory cell at a particular timing for asuitable time period during a programming cycle.

FIG. 1 illustrates an example memory device 100. The memory device 100includes a memory controller 102 and a memory cell array 104. The memorycontroller 102 includes hardware and software logic to perform variousoperations, which include programming the memory cell array 104, e.g.,writing to, reading from, or erasing from the memory cell array 104. Insome implementations, the memory controller 102 includes one or moreprocessors to program memory cells in the memory cell array 104. Forexample, the memory controller 102 can perform operations to program thememory cell array 104. The operations can be stored in a storageaccessible by the memory controller 102. In some implementations, theoperations can be stored at a flash memory or a hard disk. In someimplementations, the operations can be stored at a storage, e.g., astorage 108. In some implementations, the operations can be stored in adedicated portion of the memory cell array 104 that is distinct from thememory cells that are to be programmed.

In some implementations, the memory device 100 does not include thememory controller 102. In these implementations, the memory device 100can communicate with a device that is external to the memory device 100and the external device controls various operations performed withrespect to the memory cell array 104. For example, the external devicecan include one or more computers to perform programming operations tothe memory cell array 104. In some implementations, control signals canbe transferred between the memory device 100 and the external devicethrough suitable input/output ports. In some other implementations, thememory device 100 can include the memory controller 102 and communicatewith an external device to perform operations to the memory cell array104. For example, some operations can be controlled by the memorycontroller 102 and other operations can be controlled by the externaldevice.

The memory cell array 104 includes one or more memory blocks. In someimplementations, each of the memory blocks may include a plurality ofword lines. A plurality of memory chunks can be coupled to each wordline. A memory chunk can include a plurality of memory cells. In someimplementations, a particular number of memory cells are grouped as onememory chunk. For example, one memory chunk can include 16, 32 or 64memory cells. Memory chunks will be described in greater detail withreference to FIGS. 3A and 3B.

The memory cells in the memory cell array 104 can be single-level cellsor multi-level cells. In some implementations, the memory cell array 104includes nonvolatile memory cells, e.g., a flash memory cells. However,the memory cell array 104 can include any type of memory cellsincluding, but not limited to, 2D NAND flash memory cells, 3D NAND flashmemory cells comprising U-shaped strings, 3D NAND flash memory cellscomprising non-U-shaped strings, and NOR flash memory cells.

The memory device 100 further includes an error detection circuit 106.The error detection circuit 106 separately detect errors for eachparticular memory block in the memory cell array 104. For example, theerror detection circuit 106 can be an error bit count (EBC) circuit thatcounts a number of errors occurring in a particular memory block for aparticular time period. The counted number of errors can be reported tothe memory controller 102 such that the memory controller 102 candetermine a status of the memory block based on the numbers of errors.For example, where the counted number of errors does not satisfy, e.g.,is less than, a first threshold, the memory controller 102 can determinethat a status of the memory block is good. As another example, where thecounted number of errors satisfies, e.g., is more than, the firstthreshold, but does not satisfy, e.g., is less than, a second threshold,the memory controller 102 can determine that a status of the memoryblock is wear-out. As another example, where the counted number oferrors satisfies, e.g., is more than, the second threshold, the memorycontroller 102 can determine that a status of the memory block isbroken. Rather reporting a counted number of errors, the error detectioncircuit 106 can report an error rate, e.g., a number of errors per unittime, for a memory block. The controller 102 can compare the error rateto a threshold error rate to determine the status of the memory block.

In some implementations, the memory controller 102 can perform differentprogramming operations based on a status of a cell. For example, where astatus of a cell is good, the memory controller 102 can performmulti-level programming operations to the memory block. As anotherexample, where a status of a cell is wear-out or broken, the memorycontroller 102 can perform one-shot programming operations to the memoryblock instead of the multi-level programming operations.

In some implementations, even where a status of a cell is good, thememory controller 102 can perform one-shot programming operations to thememory block. For example, where the memory device 100 needs highreliability, the memory controller 102 can perform one-shot programmingoperations to the memory block instead of the multi-level programmingoperations. The multi-level programming operations and the one-shotprogramming operations will be described in greater detail below withreference to FIGS. 7A and 7B.

In some implementations, the memory device 100 can further include astorage 108 to store information for programming memory cells in thememory cell array 104. For example, the information can include voltagedata to perform programming operations, timing data to define one ormore time periods during which particular voltage levels are applied tothe memory cell array 104. A variety of formats are possible for thetiming data for the different voltage levels are applied to the memorycell array, e.g., a start timing and an end timing for a particularvoltage level, or a start timing and a durations for the particularvoltage level. The storage 108 can be any type of suitable storage. Forexample, the storage 108 can be static random access memory (SRAM), NANDflash memory, or a set of registers. In some implementations, thestorage 108 can be a temporary storage. In some implementations, thestorage 108 can be implemented as a portion of the memory cell array104, which can be distinct from the memory cells that are to beprogrammed.

FIG. 2 illustrates an example hierarchy of a memory cell array 204 in amemory device 200. For example, the memory cell array 204 can be thememory cell array in FIG. 1 and the memory device 200 can be the memorydevice 100 in FIG. 1. For convenience, FIG. 2 is illustrated such thatthe memory device 200 includes only the memory cell array 204. However,like the memory device 100 in FIG. 2, the memory device 200 can includeany suitable elements such as a memory controller and a storage asdescribed with reference to FIG. 1.

The memory cell array 204 includes a plurality of memory blocks. Forexample, the memory cell array 204 can include a particular number ofmemory blocks MB0-MBX-1 (e.g., X={2, 3, 4, . . . }). A memory controllerof the memory device 200 can program data to one or more memory cells inthe memory blocks MB0-MBX-1. In some implementations, the memory blocksMB0-MBX-1 can have the same structure. In some implementations, somememory blocks of the memory blocks MB0-MBX-1 can have the same structureand other memory blocks of the memory blocks MB0-MBX-1 can have adifferent structure.

Each memory block of the memory blocks MB0-MBX includes a plurality ofword lines. For example, the memory block MB1 can include word linesWL0-WLY-1 (e.g., Y={2, 3, 4, . . . }). In some implementations, othermemory blocks of the memory blocks MB0-MBX-1 can also include the samenumber of word lines. In some implementations, other memory blocks ofthe memory blocks MB0-MBX-1 can include a different number of wordlines. For example, where the memory block MB1 includes 128 word lines,the memory block MB0 can include 64 word lines.

Each word line of the word lines WL0-WLY-1 includes a plurality ofmemory chunks. For example, the word line WL1 can include memory chunksMC0-MCZ-1 (e.g., Z={2, 3, 4, . . . }). In some implementations, otherword lines of the word lines WL0-WLY-1 can also include the same numberof word lines. For example, each of the word lines WL0-WLY-1 can include128 memory chunks. In some implementations, other word lines of the wordlines WL0-WLY-1 can include a different number of word lines. Forexample, where the word line WL1 includes 128 memory chunks, the wordline WL0 can include 64 memory chunks.

FIGS. 3A to 3C illustrate example memory chunks of a memory device. Thememory chunk includes a plurality of memory cells. In someimplementations, a memory chunk can include a group of memory cells thatare used to store data. In some implementations, a memory chunk caninclude multiple groups of memory cells that are respectively used tostore data, used for a redundancy. In some implementations, a memorychunk can further include one or more shielding areas to protect memorycells that are used to store data.

FIG. 3A illustrate a first example of a memory chunk. For example, thememory chunk 310 in FIG. 3A can be one memory chunk of the memory chunksMC0-MCZ-1 in FIG. 2. In this example, the memory chunk 310 includes afirst group of memory cells 311 that are used to store data and a secondgroup of memory cells 313 that are used for a redundancy, e.g., anerror-correction code (ECC). That is, a memory controller can programdata to the first group of memory cells 311 and store an ECC that isused for detecting or correcting internal data corruption in the secondgroup of memory cells 313. In some implementations, the first group ofmemory cells 311 or the second group of memory cells 313 can include asingle memory cell.

FIG. 3B illustrate a second example of a memory chunk. For example, thememory chunk 320 in FIG. 3B can be one memory chunk of the memory chunksMC0-MCZ-1 in FIG. 2. In this example, the memory chunk 320 includes afirst group of memory cells 321 that are used to store first data, asecond group of memory cells 323 that are used to store second data, anda third group of memory cells 325 that are used for a redundancy, e.g.,a parity. Since the memory chunk 320 includes two groups of memory cells321 and 323, a memory controller can program different data, e.g., Data1 or Data 2, to the first group of memory cells 321 or the second groupof memory cells 323, respectively. In addition, the memory controllercan use the third group of memory cells 325 as a parity. Where thememory controller fails to program data to the first group of memorycells 321 or the second group of memory cells 323, the memory controllercan use data stored in the third group of memory cells 325 to create areplacement storage area. In some implementations, the first group ofmemory cells 321, the second group of memory cells 323, or the thirdgroup of memory cells 325 can include a single memory cell.

FIG. 3C illustrate a third example of a memory chunk. For example, thememory chunk 330 in FIG. 3C can be one memory chunk of the memory chunksMC0-MCZ-1 in FIG. 2. In this example, the memory chunk 330 includes aplurality of memory cells 332, 334, and 336 that are respectively usedto store data, e.g., one-bit data, and a plurality of shielding areas331, 333, 335, 337, and 339. Each memory cell of the memory cells isshielded by respective shielding areas. For example, the memory cell 332is shielded by the shielding areas 331 and 333, the memory cell 334 isshielded by the shielding areas 333 and 335, and the memory cell 336 isshielded by the shielding areas 337 and 339. In some implementations,memory cells in a memory chunk, e.g., memory cells 332, 334, and 336,are respectively coupled to bit lines. With reference to FIG. 3C, thememory chunk 330 includes n (n=2, 3, 4, . . .) memory cells that arerespectively coupled to n bit lines. For example, for n =8, the memorychunk 330 includes 8 memory cells that are respectively coupled to 8 bitlines. In some implementations, the number of memory cells in a memorychunk is same as the number of word lines in a memory block. In suchcases, where one memory block includes 8 word lines, for example, amemory chunk in the memory block includes 8 memory cells that arerespectively coupled to 8 bit lines.

In some implementations, when the memory controller programs the memorychunk 330, the memory controller programs only one memory cell in thememory chunk 330 during one programming cycle. For example, the memorycontroller may program only the memory cell 332 in one programming cycleand another memory cell 334 in a different programming cycle. Byprogramming one memory cell in one programming cycle, an error that canoccur between adjacent bit lines that are coupled to the same memorychunk can be prevented.

The shielding areas 331, 333, 335, 337, and 339 can protect the dataprogrammed in the memory cells 332, 334, and 336 when a memorycontroller performs reading operations or programming operations tomemory cells other than the memory cells 332, 334, and 336. AlthoughFIG. 3C illustrates that one memory cell is shielded by shielding areas,the number of memory cells shielded by shielding areas is not limited toa particular number. In some implementations, multiple memory cells canbe shielded by shielding areas. For example, instead of the memory cell332, two or more memory cells can be shielded by the shielding areas 331and 333.

FIGS. 4A and 4B illustrate example timing diagrams to performprogramming operations to memory chunks in a word line. For example, thememory block MB illustrated in FIGS. 4A and 4B can be the memory blockMB1 illustrated in FIG. 2. For convenience, the memory block MB in FIGS.4A and 4B is illustrated to include 8 word lines and 64 memory chunks.However, the numbers of word lines and memory chunks are not limited toparticular numbers and can be any suitable numbers. In this example, thememory block MB includes a plurality of word lines WL0-WL7. Each wordline of the word lines WL0-WL7 includes a plurality of memory chunksMC0-MCM63. The memory chunks MC0 in the word lines WL0-WL7 are coupledto a bit line BLO, the memory chunks MC1 in the word lines WL0-WL7 arecoupled to a bit line BL1, the memory chunks MC2 in the word linesWL0-WL7 are coupled to a bit line BL2, the memory chunks MC3 in the wordlines WL0-WL7 are coupled to a bit line BL3, the memory chunks MC4 inthe word lines WL0-WL7 are coupled to a bit line BL4, the memory chunksMC5 in the word lines WL0-WL7 are coupled to a bit line BLS, the memorychunks MC6 in the word lines WL0-WL7 are coupled to a bit line BL6, thememory chunks MC7 in the word lines WL0-WL7 are coupled to a bit lineBL7, . . . , and the memory chunks MC63 in the word lines WL0-WL7 arecoupled to a bit line BL63. Although the memory chunks are described ascoupled to one bit line, the number of bit lines that are coupled to amemory chunk is not limited to one. Any suitable number of bit lines canbe coupled to a memory chunk. For example, 8 bit lines can be coupled tothe memory chunk MC0.

FIG. 4A illustrates first example timing diagrams to perform programmingoperations to memory chunks in a word line. In this example, a memorycontroller, e.g., the memory controller 102 in FIG. 1, can program datato memory chunks in a particular order, e.g., using a sequential order,in which adjacent memory chunks in a word line are programmed insuccessive cycles.

When the memory controller programs data to memory chunks in the memoryblock MB, the memory controller programs data to a single memory chunkin one bit line during one cycle such that a disturbance is not spreadthrough the bit line. For example, during a cycle T, the memorycontroller can simultaneously program data to the memory chunk MC0 inthe word line WL0, the memory chunk MC1 in the word line WL1, the memorychunk MC2 in the word line WL2, the memory chunk MC3 in the word lineWL3, the memory chunk MC4 in the word line WL4, the memory chunk MC5 inthe word line WL5, the memory chunk MC6 in the word line WL6, and thememory chunk MC7 in the word line WL7.

During the next cycle T+1, the memory controller programs memory chunkssequentially, e.g., program data to memory chunks that are immediatelyadjacent to the memory chunks programmed during the cycle T. Forexample, during the cycle T+1, the memory controller can program data tothe memory chunk MC1 in the word line WL0, the memory chunk MC2 in theword line WL1, the memory chunk MC3 in the word line WL2, the memorychunk MC4 in the word line WL3, the memory chunk MC5 in the word lineWL4, the memory chunk MC6 in the word line WL5, the memory chunk MC7 inthe word line WL6, and the memory chunk MC8 in the word line WL7. Insome implementations, a different order to program data to memory chunkscan be used. In some implementations, the memory controller can programall the memory chunks in word lines during multiple cycles. For example,the memory controller can program data to 64 memory chunks in word linesduring 64 cycles.

FIG. 4B illustrates second example timing diagrams to performprogramming operations to memory chunks in a word line. In this example,a memory controller, e.g., the memory controller 102 in FIG. 1, canprogram data to memory chunks in each word line in a random order. Insome implementations, although the programming operations is performedin a random order, the memory controller does not program a memory chunkthat has been programmed during one of the previous programming cycles.

When the memory controller programs data to memory chunks in the memoryblock, the memory controller programs data to a single memory chunk inone bit line during one cycle such that a disturbance is not spreadthrough the bit line. For example, during a cycle T, the memorycontroller can program data to the memory chunk MC3 in the word lineWL0, the memory chunk MC0 in the word line WL1, the memory chunk MC5 inthe word line WL2, the memory chunk MC1 in the word line WL3, the memorychunk MC6 in the word line WL4, the memory chunk MC4 in the word lineWL5, the memory chunk MC2 in the word line WL6, the memory chunk MC7 inthe word line WL7.

During the next cycle T+1, the memory controller can program data tomemory chunks that are not programmed during the cycle T. In addition,the memory controller programs data to a single memory chunk in one bitline during one cycle. For example, during the cycle T+1, the memorycontroller can program data to the memory chunk MC0 in the word lineWL0, the memory chunk MC2 in the word line WL1, the memory chunk MC6 inthe word line WL2, the memory chunk MC5 in the word line WL3, the memorychunk MC4 in the word line WL4, the memory chunk MC7 in the word lineWL5, the memory chunk MC1 in the word line WL6, the memory chunk MC3 inthe word line WL7. In some implementations, the memory controller canprogram all the memory chunks in word lines during multiple cycles. Forexample, the memory controller can program data to 64 memory chunks inword lines during 64 cycles.

FIGS. 5A and 5B illustrate example timing diagrams to performprogramming operations to word lines of a memory block. For example, thememory block MB illustrated in FIGS. 4A and 4B can be the memory blockMB1 illustrated in FIG. 2. For convenience, the memory block MB in FIGS.4A and 4B is illustrated to include 8 word lines. However, the number ofword lines is not limited to a particular number and can be any suitablenumber.

FIG. 5A illustrates a first example timing diagram to performprogramming operations to word lines in a memory block MB. The memoryblock MB includes a plurality of word lines WL0-WL7. In this example, amemory controller, e.g., the memory controller 102 in FIG. 1, selectsword lines to program memory chunks of the word line in a particularorder, e.g. a sequential order of the word lines.

As shown in FIG. 5A, during a cycle T, the memory controller selects theword line WL1 to program data to one or more memory chunks in the wordline WL1. During the next cycle T+1, the memory controller selects aword line sequentially, e.g., the word line WL2 that is next to the wordline WL1, to program data to memory chunks in the word line WL2.

However, in some implementations, a different order to select a wordline is used. For example, the memory controller can select the wordline WL1 during the cycle T, the word line WL3 during the cycle T+1, andthe word line WL5 during a cycle T+2. In some implementations, thememory controller is configured to select all word lines within a setnumber of cycles. For example, each cycle the memory controller canselect a previously unselected word line until all of the word lineshave been selected. At this point, the process can reset. For example,the memory controller can select 8 word lines during 8 cycles.

In some implementations, as described below with reference to FIG. 5B, amemory controller, e.g., the memory controller 102 in FIG. 1, selectsword lines in a random order to program memory chunks. In such cases,although the programming operations is performed in a random order, thememory controller does not program a word line that has been programmedduring one of the previous programming cycles.

As shown in FIG. 5B, during a cycle T, the memory controller selects aword line WL1 to program data to one or more memory chunks in the wordline WL1. During the next cycle T+1, the memory controller selectsanother word line in a random order, e.g., the word line WL5, that isnot selected during the cycle T, to program data to memory chunks in theword line WL5. During the cycle T+2, the memory controller can randomlyselect yet another word line, e.g., the word line WL3, that is notselected during the previous cycles T and T+1, to program data to memorychunks in the word line WL3. In some implementations, the memorycontroller is configured to select all word lines within a set number ofcycles. For example, in each cycle the memory controller can select apreviously unselected word line until all of the word lines have beenselected. At this point, the process can reset. For example, the memorycontroller can select 8 word lines during 8 cycles.

FIG. 6 illustrates an example diagram of one-shot programming operationsfor a particular memory chunk in a memory block. For example, the memoryblock MB in FIG. 6 can be the memory block MB1 illustrated in FIG. 2.The memory block MB includes a plurality of word lines WL1, WL2, , WLM(M=2, 3, 4, . . . ). Each of these word lines includes a plurality ofmemory chunks. For example, the word line WL2 includes L (L=2, 3, 4, . .. ) memory chunks MC21, MC22, MC2L. In some implementations, a memorychunk is coupled to a particular number of bit lines. For example, eachof the memory chunks MC12, MC22, MCM2 can be coupled to N (N=2, 3, 4, .. . ) bit lines BL1-BLN.

In some implementations, each memory chunk of the memory chunks MC21,MC22, . . . MC2L are coupled to the same number of bit lines. In otherimplementations, different memory chunks of the memory chunks MC21,MC22, M2L are coupled to different numbers of bit lines.

In this example, an error detection circuit, e.g., the error detectioncircuit 106 in FIG. 1, detects an error rate of the memory block MB andreports the error rate to a memory controller, e.g., the memorycontroller 102 in FIG. 1. In some implementations, rather than reportinga counted number of errors, the error detection circuit 106 can reportan error rate, e.g., a number of errors per unit time, for a memoryblock. The memory controller determines a status of the memory block MBbased on the error rate of the memory block MB, e.g., the controller 102can compare the error rate to a threshold error rate to determine thestatus of the memory block.

Once the memory controller determines the status of the memory block MB,the memory controller can determine which programming operations thememory controller will perform to program data to the memory block MB.For example, where the status of the memory block MB is wear-out or bad,the memory controller can determine to perform a one-shot programmingoperation to program data to the memory block. In other cases, where thestatus of the memory block MB is good, the memory controller candetermine to perform multi-level programming operations to program datato the memory block MB. In some implementations, even where the statusof the memory block MB is good, the memory controller can determine toperform the one-shot programming operation to program data to the memoryblock MB if the memory device requires high reliability. In someimplementations, the one-shot programming operation is also referred toas chunk operation, in which a particular memory chunk, out of severalmemory chunks that are coupled to a word line, is programmed in aprogramming cycle, by applying a program voltage to the memory blockthat includes the particular memory chunk.

In case the memory controller determines that a chunk operation orone-shot programming operation is to be performed, the memory controllerselects a particular word line in the memory block MB using the methodsdescribed with reference to FIGS. 5A and 5B, and selects a particularmemory chunk in the selected word line using the methods described withreference to FIGS. 4A and 4B. For example, in some implementations, thememory controller selects individual word lines in a sequential order ofselecting the word lines, as described with reference to FIG. 5A. Inother implementations, the memory controller selects individual wordlines in a random order of selecting the word lines, as described withreference to FIG. 5B. In either case, the memory controller programs, insome implementations, memory chunks corresponding to the selected wordline in sequential order in successive programming cycles, e.g., asdescribed with reference to FIG. 4A. However, in other implementations,the memory controller programs memory chunks corresponding to theselected word line in a random order in successive programming cycles,e.g., as described with reference to FIG. 4B.

In some implementations, in the one-shot programming operation, thememory controller performs programming operations to a single memorychunk from a group of memory chunks that are coupled to a group of bitlines in one cycle. For example, as shown in FIG. 6, multiple memorychunks MC12, MC22, MCM2 are coupled to a group of bit lines BL1, , BLN.In this example, in performing the chunk operation, the memorycontroller programs data to only one of the memory chunks MC12, MC22,MCM2 that are coupled to the bit lines BL1, , BLN, in a particularprogramming cycle. By programming a single memory chunk during onecycle, the disturbance that can occur between multiple memory chunksthat are coupled to the same bit lines can be significantly reduced oreliminated. This improves the reliability of the memory device.

In some implementations, the memory controller performs chunk operationsbased on particular rules. For example, the memory controller canperform chunk operations based on the following rules.

-   -   Rule 1: 0≤X_(M)≤M    -   Rule 2: X₁+X₂+ . . . +X_(M)≤M        X_(M) indicates the number of programmed memory chunks for a        particular word line WLM (M =1, 2, 3, . . . ). For example, Xi        indicates the number of programmed memory chunks for the word        line WL1 and X2 indicates the number of programmed memory chunks        for the word line WL2. To verify that programming operations        have been performed correctly, the memory controller counts the        number of programmed memory chunks for each word line. For        example, as shown in FIG. 6, for the word line WL1, no memory        chunk has been programmed among memory chunks MCM1-MCML. For the        word line WL2, the memory chunk MC22 has been programmed among        memory chunks MC21-MC2L. For the word line WLM, the memory        chunks MCM1 and MCML have been programmed among memory chunks        MCM1-MCML. Based on the counting, the memory controller        determines that X₁ is 0, X₂ is 1, and X_(M) is 2. Assuming        M=192, the memory controller determines that X₁, X₂, and X₁₉₂        satisfy Rule 1 and X₁+X₂+. . . +X₁₉₂ satisfy Rule 2. As a        result, the memory controller can verify that the memory chunks        have been correctly programmed based on the rules.

FIGS. 7A and 7B illustrate example diagrams to perform programmingoperations to a particular memory block. In these examples, a memorycontroller, e.g., the memory controller 102 in FIG. 1, can performprogramming operations to program data to a memory block, e.g., thememory block MB in FIG. 6.

FIG. 7A illustrates an example diagram to perform multi-levelprogramming operations during one programming cycle. The programmingcycle includes a plurality of stages 400. In each stage, the memorycontroller provides a program voltage pulse, followed by a series ofverify voltage pulse. The number of stages 400 can be equal to thenumber of data states to which the memory cells can be programmed (orone less than the total number of states, including the erase state).For example, if a cell can be programmed as Data A, Data B, or Data C,there can be three stages.

If the memory controller is programming a target word line, it appliesthe program voltage pulse to the target word line. For example, thememory controller can apply a program voltage VP1 in the first stage, aprogram voltage VP2 in the second stage, etc. The program voltage foreach consecutive stage can be larger than the program voltage for theprior stage.

If a cell in the target word line needs remain in its present state(either erased or in a given Data state), the memory controller willapply an “on” or “high” voltage, e.g., the Vcc voltage, to the bit linefor the cell. This will inhibit the cell from being programmed.Otherwise, e.g., if a cell in the target word line is to be programmed,the memory controller will apply ground on the bit line for the cell.This will program the selected cell.

Within each stage, after applying the program voltage pulse, the memorycontroller applies a sequence of verify voltage pulses. The number ofverify voltage pulses can be equal to the number of data states (or oneless than the total number of states including the erase state) to whichthe memory cells of can be set. For example, if there are four states(Data A, Data B, Data C and Erase), then the memory controller can applya sequence of three verify voltage pulses with verify voltagesV_(verify A), V_(verifyB) and V_(verifyC), respectively. The verifyvoltage for each verify voltage pulse in the sequence can be larger thanthe verify voltage for the prior verify voltage pulse. Each verifyvoltage can be associated with a respective data state. For example,verify voltages V_(verify)A, V_(verifyB) and V_(verifyC) can beassociated with Data A, Data B, Data C, respectively.

Using the verify voltage pulses, the memory controller can confirmwhether the threshold voltage of a given cell has reached that verifyvoltage or not. If the voltage threshold of the cell has reached theverify voltage associated with the desired data for the cell, then thecell should not be programmed in the next stage. On the other hand, ifthe voltage threshold of the cell has not reached the verify voltageassociated with the desired data for the cell, then the cell should beprogrammed in the next stage. For example, if the memory controller isto program a cell to have Data B, then after each programming pulse, thememory controller can determine whether the threshold voltage of thecell has reached the V_(verifyB). If the threshold voltage of the cellhas reached V_(verifyB), then during the next stage the cell should notbe programmed, so the memory controller should apply Vcc on the bitline. On the other hand, if the threshold voltage of the cell has notreached V_(verifyB), then during the next stage the memory controllershould apply ground on the bit line to program the cell.

FIG. 7B illustrates an example diagram to perform chunk or one-shotprogramming operations for one programming cycle. During the programmingcycle, the memory controller provides a program voltage VP to programdata to a particular memory chunk, e.g., the memory chunk MC1 in FIG. 6,of the memory block. In this example, since the memory controllerprograms data using the program voltage VP, e.g., a voltage that ishigher than the program voltage VP1, the processes for erasing data arenot necessary. While programming data using the program voltage VP, thedata programmed in the memory chunk can be erased without additionalerasing processes. In addition, since the memory controller programsdata to a single memory chunk, multiple processes to program multi-leveldata, e.g., Data A, Data B and Data C, are not necessary. Thus, thememory controller can perform programming operations faster than is thecase for multi-level programming operations. Moreover, the memorycontroller programs data to a single memory chunk such that thedisturbance between two memory chunks cannot occur in the memory block.In some implementations, the program voltage VP is set to a valuebetween 12 V (volts) and 26 V.

With reference to FIGS. 7A and 7B, the gap “Gap B” between the erasevoltage level and the program voltage level is larger than the gap “GapA” between the erase voltage level and the lowest program voltage level.Thus, the memory device programmed using the one-shot programming methodin FIG. 7B has larger tolerance than the memory device programmed usingthe method in FIG. 7A, by reducing or eliminating read disturbance.

The disclosed and other examples can be implemented as one or morecomputer program products, for example, one or more modules of computerprogram operations encoded on a computer readable medium for executionby, or to control the operation of, data processing apparatus. Theimplementations can include single or distributed processing ofalgorithms. The computer readable medium can be a machine-readablestorage device, a machine-readable storage substrate, a memory device,or a combination of one or more them. The term “data processingapparatus” encompasses all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. The apparatus caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a standalone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment.

The processes and logic flows described in this document can beperformed by one or more programmable processors executing one or morecomputer programs to perform the functions described herein. Theprocesses and logic flows can also be performed by, and apparatus canalso be implemented as, special purpose logic circuitry, e.g., an FPGA(field programmable gate array) or an ASIC (application specificintegrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Computerreadable media suitable for storing computer program operations and datacan include all forms of nonvolatile memory, media and memory devices,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices. The processor and the memory can besupplemented by, or incorporated in, special purpose logic circuitry.

While this document may describe many specifics, these should not beconstrued as limitations on the scope of an invention that is claimed orof what may be claimed, but rather as descriptions of features specificto particular embodiments. Certain features that are described in thisdocument in the context of separate embodiments can also be implementedin combination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination in some cases can be excisedfrom the combination, and the claimed combination may be directed to asub-combination or a variation of a sub-combination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.

Only a few examples and implementations are disclosed. Variations,modifications, and enhancements to the described examples andimplementations and other implementations can be made based on what isdisclosed.

What is claimed is:
 1. A memory device, comprising: a memory cell arraythat includes a plurality of memory blocks, wherein a memory block ofthe plurality of memory blocks includes a plurality of word lines and aplurality of memory cells grouped into memory chunks, wherein aplurality of memory chunks is coupled to at least one of the word lines;an error detection circuit that is configured to detect one or moreerrors that occur in the plurality of memory blocks and generatecorresponding error rates; and a memory controller that is configured toprogram data to a particular memory block of the plurality of memoryblocks by performing operations that include: obtaining, from the errordetection circuit, an error rate corresponding to the particular memoryblock; comparing the error rate to a threshold value; determining astatus of the particular memory block in response to comparing the errorrate to the threshold value; based on the status of the particularmemory block, determining which programming operation to perform betweena first programming operation and a second programming operation; andperforming the determined programming operations to one or more memorychunks in the particular memory block.
 2. The memory device of claim 1,wherein the first programming operation comprises a one-shot programmingoperation and the second programming operation comprises a multi-levelprogramming operation, and wherein determining which programmingoperation to perform comprises: based on comparing the error rate to thethreshold value, determining that the error rate is less than thethreshold value; in response to determining that the error rate is lessthan the threshold value, determining that the status of the particularmemory block is good; and upon determining that the status of theparticular memory block is good, selecting the multi-level programmingoperation and performing the multi-level programming operation to one ormore memory chunks in the particular memory block.
 3. The memory deviceof claim 1, wherein the first programming operation comprises a one-shotprogramming operation and the second programming operation comprises amulti-level programming operation, and wherein determining whichprogramming operation to perform comprises: based on comparing the errorrate to the threshold value, determining that the error rate is greaterthan the threshold value; in response to determining that the error rateis greater than the threshold value, determining that the status of theparticular memory block is wear-out or bad; and upon determining thatthe status of the particular memory block is wear-out or bad, selectingthe one-shot programming operation and performing the one-shotprogramming operation to one or more memory chunks in the particularmemory block.
 4. The memory device of claim 3, wherein performing theone-shot programming operation to one or more memory chunks in theparticular memory block comprises: selecting a particular word line froma plurality of word lines in the particular memory block; selecting aparticular memory chunk from a plurality of memory chunks in theparticular memory block that are coupled to the particular word line;and applying a program voltage to the particular memory block to programdata to the particular memory chunk.
 5. The memory device of claim 4,wherein the memory controller is configured to select one or more of theplurality of word lines sequentially or randomly.
 6. The memory deviceof claim 4, wherein the memory controller is configured to select one ormore of the plurality of memory chunks sequentially or randomly.
 7. Thememory device of claim 3, wherein performing the one-shot programmingoperation to one or more memory chunks in the particular memory blockcomprises: selecting one or more first memory chunks in the particularmemory block, applying a first program voltage to the particular memoryblock to program data to the one or more first memory chunkssimultaneously, selecting one or more second memory chunks in theparticular memory block, and applying a second program voltage to theparticular memory block to program data to the one or more second memorychunks simultaneously.
 8. The memory device of claim 1, whereinperforming the determined programming operations to the particularmemory block comprises performing one-shot programming operations to theone or more memory chunks in the particular memory block by providing aprogram voltage between 12 V and 26 V.
 9. The memory device of claim 1,wherein the particular memory block further comprises a plurality of bitlines, each of the bit lines being respectively coupled to one or morememory chunks of a plurality of memory chunks in the particular memoryblock, wherein the memory controller is configured to program data tothe particular memory block by programming, during a single cycle of theprogramming operation, an individual memory chunk of one or more memorychunks coupled to a bit line of the plurality of bit lines.
 10. A methodperformed by a memory controller to program data in a memory device, themethod comprising: obtaining, from an error detection circuitcorresponding to the memory device, an error rate corresponding to aparticular memory block of a plurality of memory blocks included in amemory cell array of the memory device, wherein a memory block of theplurality of memory blocks includes a plurality of word lines and aplurality of memory cells grouped into memory chunks, wherein aplurality of memory chunks is coupled to at least one of the word lines,and wherein the error detection circuit is configured to detect one ormore errors that occur in the plurality of memory blocks and generatecorresponding error rates; comparing the error rate to a thresholdvalue; determining a status of the particular memory block in responseto comparing the error rate to the threshold value; based on the statusof the particular memory block, determining which programming operationto perform between a first programming operation and a secondprogramming operation; and performing the determined programmingoperations to one or more memory chunks in the particular memory block.11. The method of claim 10, wherein the first programming operationcomprises a one-shot programming operation and the second programmingoperation comprises a multi-level programming operation, and whereindetermining which programming operation to perform comprises: based oncomparing the error rate to the threshold value, determining that theerror rate is less than the threshold value; in response to determiningthat the error rate is less than the threshold value, determining thatthe status of the particular memory block is good; and upon determiningthat the status of the particular memory block is good, selecting themulti-level programming operation and performing the multi-levelprogramming operation to one or more memory chunks in the particularmemory block.
 12. The method of claim 10, wherein the first programmingoperation comprises a one-shot programming operation and the secondprogramming operation comprises a multi-level programming operation, andwherein determining which programming operation to perform comprises:based on comparing the error rate to the threshold value, determiningthat the error rate is greater than the threshold value; in response todetermining that the error rate is greater than the threshold value,determining that the status of the particular memory block is wear-outor bad; and upon determining that the status of the particular memoryblock is wear-out or bad, selecting the one-shot programming operationand performing the one-shot programming operation to one or more memorychunks in the particular memory block.
 13. The method of claim 12,wherein performing the one-shot programming operation to one or morememory chunks in the particular memory block comprises: selecting aparticular word line from a plurality of word lines in the particularmemory block; selecting a particular memory chunk from a plurality ofmemory chunks in the particular memory block that are coupled to theparticular word line; and applying a program voltage to the particularmemory block to program data to the particular memory chunk.
 14. Themethod of claim 13, further comprising: selecting one or more of theplurality of word lines sequentially or randomly, or selecting one ormore of the plurality of memory chunks sequentially or randomly.
 15. Themethod of claim 12, wherein performing the one-shot programmingoperation to one or more memory chunks in the particular memory blockcomprises: selecting one or more first memory chunks in the particularmemory block, applying a first program voltage to the particular memoryblock to program data to the one or more first memory chunkssimultaneously, selecting one or more second memory chunks in theparticular memory block, and applying a second program voltage to theparticular memory block to program data to the one or more second memorychunks simultaneously.
 16. The method of claim 10, wherein performingthe determined programming operations to the particular memory blockcomprises performing one-shot programming operations to the one or morememory chunks in the particular memory block by providing a programvoltage between 12 V and 26 V.
 17. A memory controller, comprising: oneor more processors to program data to a memory cell array in a memorydevice, wherein the one or more processors are configured to executeinstructions to perform operations comprising: obtaining, from an errordetection circuit included in the memory device, an error ratecorresponding to a particular memory block of a plurality of memoryblocks included in a memory cell array of the memory device, wherein amemory block of the plurality of memory blocks includes a plurality ofword lines and a plurality of memory cells grouped into memory chunks,wherein a plurality of memory chunks is coupled to at least one of theword lines, and wherein the error detection circuit is configured todetect one or more errors that occur in the plurality of memory blocksand generate corresponding error rates; comparing the error rate to athreshold value; determining a status of the particular memory block inresponse to comparing the error rate to the threshold value; based onthe status of the particular memory block, determining which programmingoperation to perform between a first programming operation and a secondprogramming operation; and performing the determined programmingoperations to one or more memory chunks in the particular memory block.18. The memory controller of claim 17, wherein the first programmingoperation comprises a one-shot programming operation and the secondprogramming operation comprises a multi-level programming operation, andwherein determining which programming operation to perform comprises:based on comparing the error rate to the threshold value, determiningthat the error rate is less than the threshold value; in response todetermining that the error rate is less than the threshold value,determining that the status of the particular memory block is good; andupon determining that the status of the particular memory block is good,selecting the multi-level programming operation and performing themulti-level programming operation to one or more memory chunks in theparticular memory block.
 19. The memory controller of claim 17, whereinthe first programming operation comprises a one-shot programmingoperation and the second programming operation comprises a multi-levelprogramming operation, and wherein determining which programmingoperation to perform comprises: based on comparing the error rate to thethreshold value, determining that the error rate is greater than thethreshold value; in response to determining that the error rate isgreater than the threshold value, determining that the status of theparticular memory block is wear-out or bad; and upon determining thatthe status of the particular memory block is wear-out or bad, selectingthe one-shot programming operation and performing the one-shotprogramming operation to one or more memory chunks in the particularmemory block.
 20. The memory controller of claim 19, wherein performingthe one-shot programming operation to one or more memory chunks in theparticular memory block comprises: selecting a particular word line froma plurality of word lines in the particular memory block; selecting aparticular memory chunk from a plurality of memory chunks in theparticular memory block that are coupled to the particular word line;and applying a program voltage to the particular memory block to programdata to the particular memory chunk.
 21. The memory controller of claim20, wherein the one or more processors are configured to performoperations comprising at least one of: selecting one or more of theplurality of word lines sequentially or randomly, or selecting one ormore of the plurality of memory chunks sequentially or randomly.
 22. Thememory controller of claim 19, wherein performing the one-shotprogramming operation to one or more memory chunks in the particularmemory block comprises: selecting one or more first memory chunks in theparticular memory block, applying a first program voltage to theparticular memory block to program data to the one or more first memorychunks simultaneously, selecting one or more second memory chunks in theparticular memory block, and applying a second program voltage to theparticular memory block to program data to the one or more second memorychunks simultaneously.
 23. The memory controller of claim 17, whereinperforming the determined programming operations to the particularmemory block comprises performing one-shot programming operations to theone or more memory chunks in the particular memory block by providing aprogram voltage between 12 V and 26 V.
 24. The memory controller ofclaim 17, wherein the particular memory block further comprises aplurality of bit lines, each of the bit lines being respectively coupledto one or more memory chunks of a plurality of memory chunks in theparticular memory block, wherein the one or more processors areconfigured to program data to the particular memory block byprogramming, during a single cycle of the programming operation, anindividual memory chunk of one or more memory chunks coupled to a bitline of the plurality of bit lines.